The present invention relates to an organ stop switching system, and particularly to a preset system which provides the operator with means for altering or programming the presets while retaining the economy of a preset arrangement.
An organ stop may be defined as a chromatic series of tones of like quality, one tone for each key on the organ keyboard. In practice, a distinction is made between speaking stops (stops which actuate a voice) and non-speaking stops (couplers, tremulants, echo controls, expression couplers, etc.). Stops are selected by a series of stop switches or stop tabs on the organ console which may be operated by the musician for altering the organ's tonal output, and ordinarily must be manually operated or changed each time a different tonal effect is desired.
Heretofore, combination action systems or combination capture systems have been available for electrically or mechanically storing and recovering memorized stop switch settings whereby the organist may preselect a combination of stop switch settings and later recover the same for organ operation. For recall, the organist selects a combination piston, there being one piston for each memorized or "captured" combination. Combination capture systems are ordinarily quite expensive and involve special stop switches or actuators capable of physical change in position whenever a given piston is actuated so the organist can identify or alter the selected combination. A parallel memory matrix is suitably employed for receiving inputs and providing outputs to the stop switches or actuators. Systems of this type are illustrated in U.S. Pat. No. 3,307,050 issued Feb. 28, 1967 and U.S. Pat. No. 3,497,714 issued Feb. 24, 1970 to Patrick M. Castle.
A much less expensive approach is available in a so-called preset system involving no special stop switches, since the stop switches themselves do not physically move in response to recall of a preset combination. Preset combinations are typically stored in a matrix of isolation diodes wired when the instrument is manufactured. Preset pistons are selectively operated to energize preset buses and deliver current through the isolation diodes to organ tone control circuits, usually in parallel fashion. Piston presets and stop switch settings may be added together at will, i.e. any stop switch or preset piston may empower a given tone control circuit such as a keyer, filter circuit or the like. The presets are "blind" since the stop switches do not move in response to recall, and the combinations cannot be conveniently changed by the user without rewiring the instrument. Of advantage would be an inexpensive preset system having the flexibility of a more expensive combination action.